Some medical fluids are delivered intravenously to a patient. These fluids may be delivered through an administration set having at one end a spike or cannula which is inserted into the container for the medical fluid at an administration port on the container. In such a system, fluid communication between the container and the administration set is often established by piercing a membrane within the administration port, with the cannula. The interface between the administration port and the cannula is extremely important. A good seal must be established between the cannula and the administration port so as to prevent contamination of the medical fluid, which may be blood, dextrose or saline solution or one of myriad other medical fluids. Contamination may endanger the health of the patient.
However, the administration port must be designed so as to permit insertion of the cannula into the administration port and through the pierceable membrane by medical personnel without the aid of additional equipment and without requiring a significant amount of time.
To achieve the appropriate seal without undue application of force generally requires the use of a spike having dimensions which are within precise parameters, i.e., the administration port is meant to be used with a cannula of a particular size. Further, there is usually an extremely high inverse relationship between spiking resistance during insertion of the cannula and the chances of accidental removal of the cannula during use, such as may be caused by movement of the patient. In order to provide a seal which is not prone to inadvertent removal of the cannula, the interference fit between the cannula and port is typically such that insertion of the cannula requires a significant application of force.